Vehicle-mounted surveillance systems, also termed in-car video systems, are seeing increased use in the security industry and law enforcement community as an effective means to provide an indisputable video and audio record of encounters involving officers and citizens. In these systems, a video camera is typically mounted on the police car's dashboard or windshield and is generally arranged to have a field of view of the area to the immediate front of the car. The field of view approximately corresponds to what an officer would see when seated in the car's front seat. The video camera is operatively coupled to a recording device, such as digital DVR, mounted in the police car.
In-car video systems generally employ a wireless microphone carried on the person of a law enforcement officer to record an audio soundtrack that accompanies the visual scene captured on the video recording. The audio soundtrack is an extremely valuable complement to the recorded video because it acts as a transcript of what was said, by whom and when. In some cases, the audio soundtrack is more valuable as evidence than the visual record because issues pertaining to consent, admissions, and state-of-mind of the suspect and/or officer (to cite just a few examples) may be resolved more effectively by the audio record. In some systems, additional wired microphones may be deployed in other locations within the car, such as the rear-seat passenger area, to record sounds and conversations emanating from those locations.
A video recording may be started manually by the officer, or in some systems, the video recording is started automatically when, for example, the officer activates the police car's emergency systems (such as overhead lights and/or sirens), vehicle doors are opened, the police car exceeds a threshold speed (as in the case of a pursuit) or when a vehicle speed-measuring radar unit is operated. The incident is recorded on video until the system is either manually or automatically switched off.
In-car video systems serve to enhance prosecution of traffic, DWI/DUI, and controlled dangerous substances offenses (to name just a few) by contributing detailed graphical and auditory evidence in a time-sequential manner that is inherently unbiased and objective. Such evidence is a valuable adjunct to eyewitness and officer testimony. In addition, as with other quality-improvement initiatives where conduct is surveyed and recorded, in-car video system usage has been shown to assist in the maintenance of high professional standards among law enforcement personnel. Police-community relations have improved and citizen complaints of police misconduct have lessened in many jurisdictions where in-car video systems are used, often as a result of the inherently high-quality evidence provided by such systems. Videos taken with in-car video systems are also valuable training aids to law enforcement personnel. As a result, in car video systems are widely deployed in the United States. Typically every patrol car in a police agency is equipped with an in-car video system.
In-car video systems often communicate with a remotely located server using the popular Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 wireless communication standard which specifies the use of a shared transmission medium between a wireless access point and wireless clients disposed in respective in-car video systems that need to access the network. While wireless communication and uploading of captured video to the remote server generally performs satisfactorily, a given access point can only be receiving data from one wireless client at a time. In addition, a wireless client that requests bandwidth may often be granted a disproportionate amount of bandwidth which may result in that client monopolizing the transmission channel that operates on the access point. This potential for monopolization, along with the typically bursty nature of digital transmission, and limitations imposed by the physical installation of the wireless such as interference from other RF (radio frequency) sources, may often result in less than desired throughput from the wireless clients to the access point. Lengthy times for uploading data from the wireless clients through the access point to other devices coupled to the network such as servers and storage devices may also be experienced.
Accordingly, more efficient data transmission over wireless networks is desired.